1. Field of the Invention
This invention relates to an improved applicator for tape material having a fibrous surface, and in one aspect, to an improved applicator for tape having a heat-activatable adhesive opposite the fibrous surface for applying lengths of tape to a woven material.
2. Description of the Prior Art
Dispensers for tape products and for applying discrete lengths of tape to articles are well known. Pressure-sensitive adhesive tape can be applied by advancing a section of the tape, cutting the section of tape and supporting the section of tape on a pad to advance the cut section of tape to an article to which it is to be applied. Examples of such dispensers are shown in U.S. Pat. No. 3,472,724, issued Oct. 14, 1969 to J. H. Casey, and U.S. Pat. No. 3,081,815 to J. W. Toensing, issued Mar. 19, 1963. Many other similar dispensers for pressure-sensitive tape are well known. In these devices however the cut section of tape is easily supported by vacuum since the backing for the tape is smooth and generally nonporous. A small amount of subatmospheric pressure will be sufficient to maintain the tape firmly against the pad during movement for application.
Dispensers are also known for dispensing lengths of a heat-activatable adhesive tape, by advancing the tape, cutting a discrete length from the strip of tape, preheating the adhesive on the tape to activate the same and applying the tape against a surface. Examples of such devices are known in the bookbinding art. One example is U.S. Pat. No. 3,715,260 of P. L. Dornemann et al, issued Feb. 6, 1973. In this device a strip of tape is advanced from a supply roll, it is cut from the roll, a heater is passed over the adhesive in spaced relationship to activate the same by radiant heating, and then the edge of the sheets to be bound is moved into contact with the adhesive on the tape and forced thereagainst until the adhesive again cools. The tape utilized is a flexible sheet material capable of withstanding heat. The tape is also generally structured such that it can be supported or moved by a pneumatic member such as in the above-mentioned pressure-sensitive adhesive tape applicators. An example of an applicator for bookbinding tape using pneumatics in U.S. Pat. No. 2,646,104 of T. B. Hawkes, issued July 21, 1953.
Conductive heating of heat-activatable adhesives by contacting the adhesive with the heating element is known, e.g., U.S. Pat. No. 2,946,281, of A. O. Sohn, issued July 26, 1960, but obtaining rapid controlled heating by assuring brief intimate contact between the adhesive coating and the high temperature heater is not known.
The handling of a tape web which has a fibrous surface on one side of the tape backing and neither the fibers nor backing are heat-resistant, e.g., they are formed of nylon, and a heat-activatable adhesive coated on the opposite side of the backing, is difficult as it cannot be supported opposite the adhesive pneumatically as in the known dispensers and the adhesive cannot be activated by convection over a long period or conduction through the backing. Further it is difficult to support cut lengths of the tape web in a fixed position and move the articles to the tape to apply the tape to the article and to apply uniform pressure across the backing of the tape to assure contact between the article and the adhesive surface.
Known systems which do not use pneumatics to support the tape are also known and one example is shown in U.S. Pat. No. 3,625,799, of D. G. Way, issued Dec. 7, 1971. In this dispensing device the cut length of tape is retained on the applicating pad by means of anchoring pins which extend from the surface of the pad and perforate the cut section of tape. The anchoring pins move vertically out of their holding position when the face of the applicating pad comes into engagement with the surface to which the tape section is to be applied. This system does not fully support the strip of tape and the projecting pins would not allow the adhesive surface to be contacted other than with the article to which it is to be applied.
Another known device for applying sections of tape having a fibrous surface is disclosed in U.S. application Ser. No. 436,874, filed Jan. 28, 1974, now U.S. Pat. No. 3,929,552, of Larry A. Bettenhausen et al., and assigned to the assignee of this application. In this prior application there is disclosed a dispenser for a fibrous tape having a pressure-sensitive adhesive coating opposite the fibrous surface. The cut length of tape is held against a pad by a pair of fingers extending around opposed edges of the tape. The pad and fingers move the tape into contact with the article and a plunger then holds the tape while the fingers are retracted. Intimate contact of the entire adhesive coated surface to the article is not achieved except by a subsequent pressing action.
Therefore, the problem exists in being able to suitably support the entire cut length of tape which has a fibrous surface on one side of the tape and an adhesive substance on the opposite surface. It is also difficult to support the strip of material such that the adhesive surface could be moved past and into contact with a heating member to activate the adhesive to the desired depth without softening the backing or fibers. Third, it is a problem to move the tape into contact with an article or web to which it is to be applied with sufficient force to place the entire adhesive coated surface of the tape into intimate contact with the article.